A number of excavation machines are known for cutting drifts, tunnels, stopes, caverns or the like, which have a rotatable head on which a plurality of arms are mounted that extend in the direction of excavation and which are radially pivotable by means of hydraulic cylinders to achieve a desired excavation profile. One example of such a machine is disclosed in European Patent No. 0551273 which belongs to the same applicants as the present application. Another example is disclosed in German Offenlegungsschrift DE 31 40 707 and still a further example is given in U.S. Pat. No. 4,248,481. Most of these prior art references indicate that the machines in question can be used to cut various profiles, however, the actual cutting of such profiles must be done by the operator of the machine who, for example, must adjust the extension of the arms to cut corners in a rectangular profile or to cut uneven angles in profiles where such angles are desired. This leads to considerable difficulties and results in uneven excavations. Also the achieved results greatly depend on the expertise of the operator of the machine which in itself leads to a great deal of inconsistency.
It is suggested in European Patent No. 0551273 that the pivot drives for the tool arms can be controlled automatically using a computer program, however, no parameters on which such a program would be based have been defined. A general computer program could be used, but it would be difficult to adapt it to various rock conditions and various profiles that one may need to cut during the excavation.